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OptimizingSystem Performance and the User Experience with USB 3.0 采用USB 3.0优化系统性能和用户体验 By DannyTseng, Cypress 作者：Danny Tseng，赛普拉斯公司 Universal Serial Bus, or more commonlyknown as USB, is a peripheral connectivity standard that was originallyreleased in 1996. USB 1.0 includes twospeed grades, Low Speed and Full Speed, which support data rate of 1.5Mbps and12Mbps, respectively. USB 1.0 targetedto unify the interface for peripheral connectivity in PC. In 2000, USB 2.0 was released, and it addedHi-Speed USB at 480Mbps. The highermaximum bandwidth addressed the growing storage trend and the larger amount ofdata being transported between PC and peripherals. To date, there are over 6 billion USB devicesin the world, with approximately 2 billion new USB devices sold per year. 通用串行总线，即人们熟知的USB，是一种最初于1996年发布的外设连接标准。USB 1.0 包含低速和全速两个速度等级，分别支持1.5Mbps和12Mbps的数据速率。USB 1.0的目标是统一PC的外设连接接口。USB 2.0于2000年发布，其增加了数据速率为480Mbps的高速USB。这种更高的最大带宽顺应了不断增长的存储趋势，满足了PC与外设之间更大的数据量传输需求。截至到目前，全球已有超过60亿个USB设备，每年新售出的USB设备大约20亿个。 The latest addition to the USB family isthe USB 3.0 specification which boosts the maximum data transfer rate to 5Gbps,or just over 600MB/s. The USB 3.0specification is designed to be fully backward compatible. The new SuperSpeed SSTX+/- and SSRX+/-signals pairs are complemented by the legacy USB 2.0 D+/D- signals, and insystems that do not yet fully support USB 3.0, USB 2.0 can be used. USB系列的最新成员是USB 3.0规范，它将最大数据传输速率提升到了5Gbps或略高于600MB/秒。USB 3.0规范在设计上完全向后兼容，所提供的最新SuperSpeed SSTX+/-和SSRX+/-信号兼容原有USB 2.0 D+/D-信号，因此，尚未完全支持USB 3.0的系统可以使用USB 2.0。 With several products out in the marketwith USB 3.0 certification, the question really is, how long will it take formass market adoption and what will be the key drivers that promote suchadoption? 目前市场上已有几款通过USB 3.0认证的产品，真正的问题在于USB 3.0的大规模市场普及需要多长时间以及背后的主要驱动力是什么？ WhyUSB 3.0? 为什么要采用USB 3.0？ USB 3.0, code name SuperSpeed, offersseveral value propositions that greatly benefit mobile handheld devices andconsumer electronics. First, theincreased data rates of up to 5Gbps or 600MB/s provide ample bandwidth for highperformance applications. With therecent popularization of high-definition content and 3D technology, the mediafile sizes being transferred have also increased drastically. These trends were immediately reflected inthe size of the mass storage devices being shipped; new handheld devices arenow shipping with embedded and/or removable storage as big as 64GB. This trend is expected to continue as more HDand 3D content is becoming available. USB 3.0（也称作为SuperSpeed）所提出的多个价值定位都可以让移动手持设备和电子消费类产品大获裨益。首先，高达5Gbps或600MB/秒的数据速率可为高性能应用提供充足的带宽。由于最近高清内容和3D技术得到普及，使得传输的媒体文件大小也急剧增加。这些趋势可在目前发售的大容量存储设备的容量值上得以体现，新的手持设备现在配备了高达64GB的嵌入式和/或移动存储器件。随着更多高清和3D内容的出现，预计这种趋势将会继续。 Both new embedded and removable massstorage standards, eMMC 4.41 and SD 3.0, have defined densities of up to2TB. In order to keep up with theincreasing mass storage densities, the speed to sideload content onto and off ahandheld device also needs to be improved. To put things in perspective, one appropriate analogy of using USB 2.0with next generation storage is like using a small garden hose to fill anOlympic-sized swimming pool; it simply takes too long. Quantitatively, transferring 1 GB of datawith USB 2.0 takes about 60 seconds, and it can take upwards of 60 minutes totransfer 64 GB of data. Now, imagineusing USB 2.0 to transfer 2TB of data. With SuperSpeed USB 3.0, the transfer speed is increased by 10x, whichallows 64 GB of media data to be transferred in just a few minutes’ time. 新的嵌入式和移动大容量存储标准（eMMC 4.41和SD 3.0）定义了高达2TB的容量。为了跟上不断增长的大容量存储密度，在手持设备上输入和输出内容的速度也需要相应提高。形象地说，在新一代存储设备中使用USB 2.0就像是用一根小橡胶软管给奥运会标准游泳池注水一样，需要太长时间。从数量上来说，使用USB 2.0传输1 GB的数据需要大约60秒，而传输64 GB的数据需要60分钟以上。现在，想象一下使用USB 2.0传输2TB的数据是什么样子。有了SuperSpeed USB 3.0，传输速度将提高10倍，只需几分钟时间就能传输64GB的媒体数据。 BatteryLife Considerations 电池使用寿命的考虑因素 The second value proposition for USB 3.0 isits superior power management. USB 3.0introduces new power modes that allow the USB Link Layer to be independentlypowered down when a USB connection is established but not active. These new power modes allow for moreefficient use of the limited battery that powers mobile devices. In usage cases that require intermittent dataaccess over USB, e.g. video streaming and music playback, this protocol layerimprovement, along with the faster USB 3.0 speed, can drive down the overallper-bit power consumption by 80%. Moreover, the low-power Link Layer states are entered and exitedautomatically, and are designed to be transparent to the higher applicationslayer. This makes it easy for systems tomigrate to USB 3.0. USB 3.0的第二个价值在于其出色的电源管理。USB3.0引入了新的电源模式，允许在USB连接建立但未激活的情况下独立切断USB链路层的电源。这些新的电源模式允许更高效地利用有限的电池能量为移动设备供电。在要求通过USB断断续续存取数据的情况下（例如视频流和音乐播放），这种协议层的改进配合更快的USB 3.0可将每字节总体功耗降低80%。此外，低功率链路层状态可以自动进入和退出，而且对上层的应用层是透明的。这使得系统更容易迁移到USB 3.0。 FasterCharging 更快充电 USB 3.0 has also increased the amount ofcurrent that a downstream USB Device can draw from a traditional Host (e.g.PC). This limit is raised from USB 2.0’s500mA to USB 3.0’s 900mA, which translates into an 80% increase in availablepower. Not only will this enable higherperformance applications, but it also allows mobile handhelds to charge theirbatteries faster. The shortened chargetime is invaluable for end users who are always on the go. For example, to fully charge a drained1400mAh battery with an assumed 90% efficiency would take over 3 hours with aUSB 2.0 Host, but only 1.5 hour with USB 3.0. 此外，USB 3.0还增加了下游USB设备从传统主机（例如PC）中所能提取的电流量。电流限值从USB 2.0的500毫安提升至USB 3.0的900毫安，相当于可用电源增加了80%。这不仅能支持更高性能的应用，还使得移动手持设备的电池充电速度更快。对于一直在路上的最终用户来说，充电时间的缩短及其重要，例如，使用USB 2.0主机给一个效率假定为90%的耗尽电的1400mAh电池充满电需要3小时以上，而使用USB 3.0仅需1.5小时。 TheAge of HD and 3D Multimedia 高清与3D多媒体时代 HD camcorders and video-capable mobilephones are becoming increasingly popular and video sharing applications likeYouTube now support HD (1080p) formats. To store various formats of compressedand uncompressed HD video formats, we see a corresponding increase in storagedensities. Higher storage densities also means the pipe needed to fill it needsto be faster. Users do not have the patience to wait for an hour to sideloadvideo from their device to the PC for editing and sharing. USB 3.0 plays a keyrole in this new generation of high-definition content creation andconsumption. 高清摄像机和具有视频功能的手机日益普及，而且视频共享应用（比如YouTube）现在支持HD（1080p）格式。为了存储各种格式的压缩和未压缩HD视频格式，存储密度就会相应增加。更高的存储密度意味着“传输管道”也需要加快速度。用户没有耐心等待一个小时将其设备上的视频存入PC以进行编辑和共享。USB 3.0在新一代高清内容制作与使用过程中发挥了至关重要的作用。 file:///C:/Users/Zain/AppData/Local/Temp/OICE_7539DF28-48D5-4BBC-AEC7-9E00F3A9A62A.0/msohtmlclip1/01/clip_image002.gif Fig 1: Video formats and storagerequirements 图 1：视频格式与存储要求 ManufacturingFlashing 制造过程：刷机 With the value propositions describedabove, USB 3.0 can enable new usage models as well as improves on existingones. Apart from the ability to sideloadmedia content at 10x the speed of a USB 2.0 system, one of the early applicationsidentified for USB 3.0 is content/code flashing during manufacturing. The cost to manufacture a mobile handhelddevice strongly correlates to the amount of time it needs to spend in themanufacturing line, and the most time consuming part of the process is flashprogramming and preloading content. Theflashing process is often done by USB, and today, USB 2.0 is widely used in theproduction line. Not only will USB 3.0flash phones at 10x the speed, it can also be used to flash multiple devices atthe same time. Ultimately, USB 3.0 cansignificantly lower manufacturing cost. 鉴于上述价值体现，USB 3.0能够支持新的使用模式并改进现有的使用模式。除了能够以USB 2.0系统的10倍速度载入媒体内容之外，早期的USB 3.0应用之一就是生产期间的内容/代码的刷机。制造一台移动手持设备的成本主要与花在生产线上的时间有关，而该流程最耗费时间的部分就是刷写编程和预加载内容。刷机过程通常由USB完成，而且目前USB 2.0广泛应用于生产线。USB 3.0不仅能以10倍速度进行手机刷机，而且还能同时用于对多个设备进行刷机。最终，USB 3.0将可以显著降低制造成本。 Controller-lessGaming 无控制器游戏 With the introduction of new gamingplatforms like the Xbox Kinect and Sony Playstation Eye, controller-less,gesture-based gaming is becoming increasingly popular. Such applications use high resolutionsensors to capture pictures of the players, and transmit that information tothe gaming console in real time. Connectivity between these sensors and theconsole would greatly benefit by USB 3.0 speeds. 随着Xbox Kinect和Sony Playstation Eye等最新游戏平台的推出，基于手势的无控制器游戏日益普及。这些应用利用高分辨率感应器捕捉玩家的图片，并将信息实时传送到游戏控制台。感应器与控制台之间的连接功能将会大大受益于USB 3.0的速度优势。 Video-over-USB USB传输视频 With HD or 3D media content becoming widelyavailable for mobile handhelds, the next logical usage model is to find a wayto output the content onto a larger display for shared viewing. This has been a challenge for USB 2.0 basedsystems as its bandwidth severely limits the video quality. With USB 3.0 bandwidth, full 1080p HD at30FPS and 24-bit color can be easily supported even without anycompression. Furthermore, the USB 3.0Audio-Video class that is currently being defined by the USB-IF also aims tooptimize HD/3D video support for mobile handhelds. USB 3.0 interface speeds also make possiblethe transfer of multimedia-rich content including video, audio and metadata. With the availability of USB 3.0 in mobilehandhelds, system integrator will no longer require to have an additional HDMIconnector, which is both bulky and does not provide battery charging capabilitywhen connected. 鉴于移动手持设备上HD或3D媒体内容的广泛应用，下一个逻辑使用模型就是寻找一种方法将内容输出到更大的显示屏以实现共享浏览。这一直是USB 2.0系统的一个挑战，因为其带宽严重限制了视频质量。借助USB 3.0带宽，即便不进行任何压缩，也能轻易地支持24位色彩的30FPS完整1080p HD。此外，USB-IF目前正在定义的USB 3.0音频-视频类别的目的也是优化面向移动手持设备的HD/3D视频支持。USB 3.0接口速度也使得多媒体内容的传输成为可能，包括视频、音频和元数据。 鉴于移动手持设备USB3.0规范的出台，系统集成商将不再需要购买额外的HDMI连接器，该连接器不仅笨重，而且连接后也不提供电池充电功能。 Other interesting usage models in the videosegment include connecting to several displays at the same time and streamingdifferent content to each display, an application which cannot be supported byother interfaces. USB 3.0 can also support simultaneous content streamingbi-directionally. There is no conceptual limit to the number of channels thatcan be sent over one physical connection.USB 3.0 bandwidth supports upto ~500channels of DVD quality video (6Mbps over a 3Gbps pipe) and up to ~100 channelsof HD quality video (30Mbps over a 3Gbps pipe) 视频行业其它有趣的使用模型包括同时连接多个显示屏并向每个显示屏传送不同的内容，而其它接口无法支持这种应用。USB 3.0还能支持双向同步内容流。对能够通过一个物理连接发送的通道数量没有理论上的限制。USB 3.0带宽支持多达大约500个通道的DVD质量视频（通过3Gbps管道可达6Mbps）以及大约100个通道的HD质量视频（通过3Gbps管道可达30Mbps）。 New applications like webtops which allow ahandheld device to be plugged into a larger monitor and keyboard will need afaster connectivity solution for seamless user experience. USB 3.0 fits suchapplications well due to both increased bandwidth and low power capabilities. Also,in the future, displays such as TV and monitors will no longer need to be“smart”. The phone would connect to these displays to provide the “smarts” andalso drive the displays. 允许将手持设备插入更大显示器和键盘的全新应用（比如webtop）将需要更快的连接解决方案，以提供无缝的用户体验。由于带宽增加和低功耗功能，USB 3.0非常适合此类应用。另外，将来显示屏（例如电视和显示器）将不再需要是“智能的”(多功能)。手机可以连接这些显示屏，以提供“智能”(多功能)和驱动显示屏。 USB 3.0 competes with existing solutions onthe phone such as MHL and HDMI, but USB is clearly is a more ubiquitous andbroadly adopted interface. USB 3.0answers the long anticipated need for high-definition content in mobilehandhelds, and it is designed and positioned to be the ideal solution for HD/3Dcontent transfer and consumption. USB 3.0将与现有的移动设备接口解决方案（例如MHL和HDMI）竞争，但USB显然是一种更普及、采用更广泛的接口。USB 3.0满足了对移动手持设备上高清内容期待已久的需求，而且被设计和定位为HD/3D内容传输与使用的理想解决方案。 Authors: DannyTseng is a Product Marketing Manager in the DataCommunications Division at Cypress Semiconductor. He currently manages various USB 3.0 productsspecialized for the mobile handhelds segment. He worked as a Staff Applications Engineer for various Cypress productsprior to joining the USB Business Unit. He received a Bachelor of Applied Science in Honors Electrical Engineeringwith Management Science option from the University of Waterloo in 2003. 作者： DannyTseng是赛普拉斯半导体公司数据通信业务部的产品市场营销经理，目前负责管理专门面向移动手持设备市场的各种USB 3.0产品。**USB业务部之前，他曾担任赛普拉斯多种产品的主任应用工程师。2003年，Danny Tseng获得了滑铁卢大学的电子工程应用科学荣誉学士学位，选修了管理科学。 AshwiniGovindaraman is a Product Marketing Manager at Cypress Semiconductor’s USB New ProductDevelopment group. She drives the strategy and roadmap of Cypress’s USB 3.0products in addition to engaging with key customers. AshwiniGovindaraman是赛普拉斯半导体公司USB新产品开发部的产品市场营销经理。除了与重要客户接洽之外，她还负责推动赛普拉斯公司USB 3.0产品的战略与规划。她着重于消费类电子产品和PC外设连接解决方案。Ashwini拥有比拉科技学院（位于印度Pilani）的电气与电子学士学位，目前正在攻读宾夕法尼亚大学沃顿商学院（Wharton School）的MBA。
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